ML11272A171

Request for Information Regarding the Earthquake on August 23, 2011

ML11272A171
Person / Time
Site:	North Anna
Issue date:	09/30/2011
From:	Meena Khanna Division of Operating Reactor Licensing
To:	Heacock D Virginia Electric & Power Co (VEPCO)
boyle p b
References
TAC ME7050, TAC ME7051
Download: ML11272A171 (6)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 September 30, 2011 Mr. David A. Heacock President and Chief Nuclear Officer Virginia Electric and Power Company Innsbrook Technical Center 5000 Dominion Boulevard Glen Allen, VA 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNIT NOS. 1 AND 2, REQUEST FOR INFORMATION REGARDING THE EARTHQUAKE OF AUGUST 23,2011 (TAC NOS. ME7050 AND ME7051)

Dear Mr. Heacock:

The Nuclear Regulatory Commission staff is continuing its review of information submitted by the Virginia Electric and Power Company regarding activities conducted in response to the earthquake that occurred near the North Anna Power Station, Unit Nos, 1 and 2 (NAPS) on August 23, 2011.

This letter forwards requests for information on steam generators, piping and license renewal topics. Your expeditious response is requested to enable the staff to continue its review of your proposed plans for restarting the NAPS.

Sincerely,

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Meena Khanna Lead of North Anna Restart Team Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-338 and 50-339

Enclosure:

Request for Information cc w/encl: Distribution via Listserv

REQUEST FOR INFORMATION VIRGINIA ELECTRIC AND POWER COMPANY (VEPCO)

NORTH ANNA POWER STATION, UNIT NOS. 1 AND 2 DOCKET NOS. 50-338 AND 50-339 The following requests for information are related to the earthquake of August 23, 2011, that occurred in the vicinity of the North Anna Power Station, Unit Nos. 1 and 2 (NAPS). Previous requests for information were issued on September 14, September 26 and September 28.

Steam Generators (SG)

The following two questions result from review of VEPCO's Post-Earthquake Restart Readiness Plan Status Update report submitted on September 27, 2011.

1. Provide any new or updated information from the "ongoing investigation" into the source/origin of the loose parts found in the SG A hot leg channel head. Could the loose parts have broken off from a reactor coolant system (RCS) component (as opposed to having been introduced as a foreign object during a maintenance/inspection activity)? If so, how can it be assured that the subject RCS component can still perform its safety function?

2. Provide a summary of ding/dent indications found and how they compare in number and size to those observed in previous inspections.

The information requested below is focused on the scope of the licensee's assessment of the existing pipe stress analyses and inspection of the piping and asociated support systems, including inspection/evaluation methods, acceptance criteria, results, and corrective actions.

The intent of the questions is to determine whether the American Society of Mechanical Engineers (ASME) Class 1, 2, and 3 piping systems and any nonsafety-related systems that connect to safety-related systems satisfy the design basis so as to demonstrate that their structural integrity is maintained after the recent earthquake.

1. Describe in detail how the pipe stresses of ASME Class 1, 2, and 3 piping systems and any nonsafety-related piping systems which connect or could affect ASME Class 1, 2, or 3 piping systems have been evaluated considering the loading from the recent earthquake and aftershocks. The licensee should identify the pipe systems evaluated and discuss acceptance criteria, results, and corrective actions.

2. Discuss the piping systems that have and have not be been inspected, the inspection technique and its effectiveness, specific piping components examined (e.g., welds, nozzles, flanges, attachment lugs, and couplings), whether the pipe insulation is removed prior to inspection, how the structural integrity can be verified for the Enclosure

-2 inaccessible (to inspection) portion of the pipe, acceptance criteria, inspection results, and corrective actions.

3. In Enclosure 2 to the licensee's submittal dated September 17, 2011, the licensee stated that buried piping system pressure tests are being (or have been) performed on the buried portions of quench spray, recirculation spray, and service water system piping.

Discuss the details of the system pressure tests for safety-related buried piping (e.g.,

pressure used, hold time on the pressure, how leakage would be observed, and the length of pipe that is being pressure tested), acceptance criteria and results. The system pressure test can demonstrate whether a pipe is leaking, but will not be able to determine whether cracks have been initiated by the earthquake. Discuss the likelihood of crack initiation due to the earthquake. Justify how a system pressure test will ensure the structural integrity of the buried pipes without nondestructive examinations. For those safety-related buried pipes that have not and will not be tested, discuss how their structural integrity can be ensured.

4. A pipe support system includes spring and rigid hangers, rigid lateral struts, snubbers, clamps, I-beams, lugs welded to pipe, and base plates that are anchored to the building structures or walls either by bolting and/or welding. Discuss which pipe system's supports were inspected, inspection technique and its effectiveness, what parts of the supports were and were not inspected, acceptance criteria, and corrective actions.

Discuss the reevaluation of the pipe support structural analyses considering the earthquake effect, including acceptance criteria, results, and corrective actions.

5. The NRC staff understands that a leak was observed on control rod drive mechanism N2-18 canopy seal weld on the Unit 2 reactor vessel head. The staff understands that this leak may have occurred prior to the earthquake. Discuss whether the leakage occurred before or after the earthquake. If the leakage occurred before the earthquake, discuss the effect of the earthquake on the through wall flaw in the canopy seal weld.

Discuss the repair method and the schedule for completion. Also, identify any pipe systems that contain flaws in service prior to the earthquake. Discuss whether these flaws will be inspected by ultrasonic testing (UT) to ensure the flaw{s) has not grown as a result of the earthquake prior to restart. If UT will not be performed, discuss how the flaw{s) can be demonstrated to remain within the acceptance standards of the ASME Code,Section XI, IWB-3000, as a result of the earthquake.

6. For ASME Class 1 piping,Section XI, IWB-2410 requires that system pressure tests be performed during plant outages such as refueling shutdowns. For Class 2 and 3 piping, Table IWC-2500-1 and Table IWD-2500-1 require system pressure testing once per inspection period. The system pressure tests in the aforementioned ASME Code,Section XI articles may not be required because the shutdown was due to the earthquake and not as a scheduled refueling outage. Discuss whether a system leakage test will be performed on all ASME Class 1, 2, and 3 piping to demonstrate the structural integrity of the piping systems prior to restart. Discuss whether visual examination will be performed for each piping system as part of the system pressure test. For piping that is safety-related, but not ASME Code components or nonsafety

-3 related piping that is connected to safety-related piping, discuss whether this piping will be undergoing a system leakage test to demonstrate its structural integrity.

License Renewal Questions These requests for information focus on the period of extended operation. Unless specifically stated in the question, the following questions apply to all systems, structures, and components within the scope of license renewal.

Inspection/follow-u p: of the VEPCO summary report dated September 17, 2011 states that the structural component inspections were performed by qualified engineering personnel as defined in ER-NA-INS-104, "Monitoring of Structures North Anna Power Station." However, 10CFR 50.55a states that the personnel that examine containment concrete surfaces and tendon hardware, wires, or strands must meet the qualification provisions in ASME Code Section XI, IWA-2300. The "owner-defined" personnel qualification provisions in IWL-2310(d) are not approved for use. In addition, American Concrete Institute (ACI) 349.3R states that the personnel performing the inspections or testing at the plant, under the direction of the responsible-in-charge engineer, should meet one of the following qualifications:

a) Civil or structural engineering graduate of an ABET (accreditation board for engineering and technology) accredited college or university who has over 1 year of experience (or are ACI inspector certified) in the evaluation of inservice concrete structures or quality assurance related to concrete structures; or b) Personnel possessing at least 5 years experience (or are ACI inspector certified) in the inspection and testing of concrete structures and having qualifications acceptable to the responsible-in-charge engineer.

Confirm if the personnel qualification requirements specified in the VEPCO procedure meet the requirements of IWA-2300 and ACI 349.3R.

Long Term:

1. For all time-limited aging analyses (TLAA) submitted with the license renewal application and its amendments:

a) State whether the recent seismic activity has resulted in a change to the disposition of any TLAA such that the original conclusions do not remain the same.

b) For any dispositions that have changed, state the current TLAA disposition (Le., 10 CFR 54.21 (c) (1) (i), 10 CFR 54.21 (c) (1) Oi), or 10 CFR 54.21 (c) (1) (iii>>.

c) State the basis for the acceptability of the change in disposition. For example. if a disposition changed from 10 CFR 54.21 (c) (1) (i) to 10 CFR 54.21 (c) (1) (iii). state how the aging effects will be adequately managed throughout the period of extended operation.

- 4 d) According to the North Anna updated Final Safety Analysis Report. Table 5.2-4.

faulted conditions (Design Basis Earthquake) are not included in the fatigue analysis of the plant components and structures. In addition. operating basis event (OBE) earthquakes are also not included in the fatigue analysis. Therefore. for all TLAAs submitted with License Renewal Application (LRA) and its amendments: provide revised fatigue analyses that include the impact of the August 23, 2011, earthquake on the long-term operation of the plant (40-60 years). These analyses should also include the impact of earthquake aftershocks, and consider five additional OBE level earthquakes that may occur until the end period of extended operation.

2. While the staff acknowledges that a seismic event is a near singular aging event, given that the recent seismic activity exceeded the current seismic licensing basis with multiple aftershocks, state how:

a) It was concluded that no existing flaws or defects sizes were impacted such that augmented license renewal inspections need not be conducted.

b) It was concluded that no new flaws or defects occurred such that augmented license renewal inspections need not be conducted.

3. State what augmented license renewal inspections will be conducted for structures and piping/component supports to ensure that seismic displacements did not result in significant cracking for concrete and masonry walls. or loss of form for soil. or state the basis for why such inspections are not required.

4. State what augmented license renewal inspections will be conducted at displacement sensitive locations (e.g., tank nozzle connections. piping transitioning between buildings or from a building to the soil. where differential seismic movements occur) to confirm that there was no impact to the pressure boundary function, or structural and/or support function, or state the basis for why augmented inspections are not required for programs such as tank inspection activities, and buried piping and valve inspection activities.

ML11272A171 I OFFICE NRRlLPL2*1/PM NRRILPL2-1/PM NRR/LA. NRRlBC NAME RMartin PBoyle (RMartin for) CSoia MKhanna I I DATE 09/30/11 09/30/11 09/30/11 09/30/11 I